Machine tool and cover device for the machine tool

ABSTRACT

A machine tool and a cover device for the machine tool capable of preventing work cutting chips and coolant from falling on the rear part of a spindle head ( 8 ) and the operating positions of a first saddle ( 4 ) and a second saddle ( 6 ) without expanding the lateral width of the machine tool, wherein a column ( 2 ) is fixedly installed on a bed ( 1 ), the first saddle ( 4 ) is guided on the front surface of the column ( 2 ) movably in vertical direction (f 1 ), the second saddle ( 6 ) is guided on the front surface of the first saddle ( 4 ) movably in lateral direction (f 2 ), and the spindle device ( 8 ) is guided on the second saddle ( 6 ) movably in longitudinal direction (f 3 ) and, in addition, a first cover plate ( 31 ) is fixed to the second saddle ( 6 ), a side cover plate ( 33 ) is installed continuously with each of the right and left side edges of the cover plate ( 31 ) bendably in longitudinal direction (f 3 ), a second cover plate ( 39 ) is fixed integrally with the first saddle ( 4 ), and a third cover plate ( 41 ) is installed fixedly to the front side of the second cover plate ( 39 ).

FIELD OF THE INVENTION

The present invention relates to a machine tool having a specific coverdevice.

BACKGROUND OF THE INVENTION

Japanese patent publication No. 365529 of 1992 discloses a machine toolcapable of shortening the length of a spindle direction (namely,longitudinal direction) of the first saddle, the second saddle, and acolumn, and of moving a spindle head in longitudinal direction at highspeed. As shown therein, the machine tool is defined that the column isfixedly installed on a bed in the spindle direction and guides the firstsaddle to move in vertical direction. Besides, the first saddle guidesthe second saddle to move in lateral direction, and the second saddleguides the spindle head to move in longitudinal direction.

In the above machine tool, when a tool installed on the front end of thespindle head cuts a workpiece, cutting chips and coolant sometimessplash backward due to rotations of the tool. Without any protectionfrom this splash, cutting chips of the workpiece and tile coolant falldirectly on the first saddle and the second saddle. As a result, notonly machining accuracy is damaged, but also maintenance and cleaning ofthe machine tool are made difficult.

An object of the invention is to provide a machine tool having aspecific cover device free from the above problems.

SUMMARY OF THE INVENTION

To achieve the above object, a machine tool of this invention has thefollowing characters. A column is fixedly installed on a bed, and thefirst saddle is guided on the front surface of the column movably invertical direction. The second saddle is guided on the front surface ofthe first saddle movably in lateral direction, and tile spindle head isguided on the second saddle movably in longitudinal direction. To thefront surface of the second saddle is fixed the first cover plate whichallows the spindle head to move in longitudinal direction. A side coverplate is connected to each of the right and left side edges of the coverplate in such a manner that the side cover plate can bend backward dueto guiding effect of a guiding means provided between the side coverplate and the first saddle. The second cover plate covers the frontside, tie upper side and the lower side of tile first cover plate insuch a manner that the spindle head can move in lateral direction. Thesecond cover plate is fixed integrally with the first saddle, and thethird cover plate is fixedly installed to the front side of the secondcover body. The third cover plate covers the front surface of the columnin such a manner that the spindle head can move in vertical and lateraldirections.

The above first cover plate, side cover plate, second cover plate andthird cover plate can prevent cutting chips and coolant which splashfrom the tip of the spindle head from falling directly on the rear partof the spindle head, the first saddle and the second saddle.

Besides, when the second saddle moves in lateral direction, the rightand left side cover plates are prevented from bending backward and fromprotruding in lateral direction.

More concretely, the first cover plate has a through hole into which thespindle head is inserted movably in longitudinal direction. A sealingmeans is provided between the through hole and tile spindle head,thereby keeping an interval therebetween almost liquid-tightly. Withthis structure, cutting chips and coolant splashing backward from thetip end of the spindle head are prevented from getting in the back ofthe spindle head through the interval between the through hole and thespindle head.

Circular guide passages are provided to the guiding means providedbetween tile side cover plate and the first saddle.

Moreover, when the second saddle moves to either of the right and leftsides, the side cover plate on the side to which the first saddle movesbends backward centering on a position connecting with the first coverplate due to guiding effects of circular guide passages of the guidingmeans.

Besides, the side cover plate is pulled in a direction perpendicular tothe circular guide passages of the guiding means by forcing means. Thisstructure controls shake due to free space of an operating part of theside cover plate.

On the other side, the side cover plate may be formed from plural coverplate members, and these cover plate members are bendably connected witheach end.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment showing a basic structureof a machine tool of the invention.

FIG. 2 is a front view of the above basic structure.

FIG. 3 is a side view of the above basic structure.

FIG. 4 is a plane view of the above basic structure.

FIG. 5 shows a part of the above basic structure, and

FIG. 5A is a perspective view of the first saddle, and

FIG. 5B is a perspective view of the second saddle.

FIG. 6 is a perspective view of the above basic structure to which thefirst cover plate and the side cover plate are installed.

FIG. 7 shows a part of the above machine tool, and FIG. 7A is a plan eview,

FIG. 7B is a side view, and

FIG. 7C is a sectional view taken on line x—x.

FIG. 8 is a perspective view showing a part of the above machine tool.

FIG. 9 is a perspective view of the above basic structure to which thesecond cover plate, the first cover-plate and the side cover plate areinstalled.

FIG. 10 is a perspective view of the above basic structure to which thethird cover plate, the second cover plate, the side cover plate areinstalled.

FIG. 11 shows the above machine tool whose first, second and third coverplates are dotted.

FIG. 12 shows a part of the above machine tool, and

FIG. 12A is a horizontal sectional view of the second saddle when itmoves to the left end of its movable range, and

FIG. 12B is a horizontal sectional view of the second saddle when itmoves to the right end of its movable range.

PREFERRED EMBODIMENT OF THE PRESENT INVENTION

The present invention is described with reference to figures as follows.

A machine tool of this invention is a machining center. It comprises abed 1 forming the lowest part, a column 2 fixed on the upper surface ofthe bed 1, a pair of guide rails 3, 3 vertically fixed on the frontsurface of the column 2, the first saddle 4 guided by the guide rails 3,3 movably in vertical direction f1, a pair of rail members 5, 5laterally fixed on the front surface of the first saddle 4, the secondsaddle 6 guided by the rail members 5, 5 movably in lateral directionf2, a pair of rail members 7, 7 longitudinally fixed on the secondsaddle 6, and a spindle head 8 guided by the rail members 7, 7 movablyin longitudinal direction f3.

Each structure of the above is explained as follows.

The bed 1 forms a box made of steel plate. Supporting members 9, 9 forfixing a not-illustrated working table are installed on the uppersurface of the bed 1 in front of the column 2. A dropping hole 10 isprovided at the center of the bed 1 to drop cutting chips and coolantinto a specific place.

The column 2 has a pair of right and left vertical elements 2 a, 2 a anda pair of top and bottom lateral elements 2 b, 2 c. The column 2 ismainly composed of a square frame body having a relatively large squarehole “a” in longitudinal direction at the center. Here, a motor table 2d is provided to the lateral element 2 b on the upper side, and aservomotor 11 for driving the first saddle 4 in vertical direction isfixed on the motor table 2 d.

As shown in FIG. 5A, the first saddle 4 has a pair of right and leftvertical single prismatic bodies 4 a, 4 a having square cross sectionsrespectively, and a pair of top and bottom lateral single prismaticbodies 4 b, 4 c having square cross sections respectively. Here, thecenter of the first saddle 4 forms a relatively large square hole “b” inlongitudinal direction. A vertical square frame is made of steel plateswithin the size of the front surface of the column 2. An fitting member12, which is guided by the rail members 3, 3, is fixed on the rearsurface of the square frame body. A pair of rail members 5, 5 forguiding the second saddle 6 are fixed on the front surface of the topavid bottom lateral prismatic bodies 4 b, 4 c. A bracket 13 in aninverse U-shaped from the front view is secured on the rear surface ofthe top lateral prismatic body 4 b. A nut 14 is fixed on the top of thebracket 13. In this case, the single prismatic bodies 4 a, 4 b, 4 cinclude one formed by integrating plural prismatic members having asquare cross section.

A vertical screw shaft 15, which is connected to an output shaft of theservomotor 11, is screwed into the nut 14. A servomotor 16 for drivingthe second saddle 6 in lateral direction is installed on the uppersurface of the top lateral frame member 4 b. Besides, as shown in FIG.5A, a pair of reinforcing plates 17, 17 are fixed on the upper surfaceof the lateral frame member 4 b, and bearing members 19 a, 19 b whichrotatively support a lateral screw shaft 18 connected to the outputshaft of the servomotor 16 are fixed on the reinforcing plates 17, 17.

As shown in FIG. 5B, at the center of the second saddle 6 is provided alongitudinal square hole “c” into which the spindle head 8 is inserted.Besides, the second saddle 6 has a vertical square frame 6 a within thesize of the front surface of the first saddle 4. Moreover, on the rearsurface of the square frame body 6 a are secured a pair of right andleft horizontal inductive frames 6 b, 6 b made of square steel cylindermembers in longitudinal direction, and plural fitting members 20 guidedby the rail members 5, 5.

The spindle head 8 has a head frame 29 for rotatively supporting alongitudinal spindle 28. A not-illustrated drive motor for rotating thespindle 28 is provided inside the head frame 29. On the bottom surfaceof the head frame 29 are provided plural interfitting members 30 guidedby the rail members 20.

A bulging member 23 which projects obliquely upwardly to the back isprovided on one side of the upper surface of the lateral prismatic body22 on the upper side of the square frame 6 a. At the tip end of thebulging member 23 is fixed a disengaging ring-shaped nut holding member24. The lateral screw shaft 18 screws on a nut held by the nut holdingmember 24. Besides, a vertical supporting plate 26 is secured betweenthe rear parts of the right and left horizontal inductive frames 6 b, 6b, and a servomotor for driving the spindle head in a longitudinaldirection is fixed on the rear surface of the supporting plate 26.

A not-illustrated screw-nut mechanism for longitudinally moving the headframe 29 by rotation of the servomotor 27 is provided between the headframe 29 and the servomotor 27.

A cover device is installed on the basic structure of thus formedmachine tool. A concrete structure is explained with reference to FIG. 6to FIG. 11.

As shown in FIG. 6, the first cover plate 31 is fixed on the frontsurface of the second saddle 6, covering almost the whole thereof. Atthe center of the first cover plate 31 is provided a through hole 8 ainto which the spindle head 8 is inserted in longitudinal direction. Atthe inner circumference of the through hole 8 a is fixed a sealing means32 to seal an interval between the spindle head 8 and the through hole 8a almost liquid-tightly. For example, a flexible belt-like rubber isused as the sealing means 32.

A side cover plate 33 is connected to each of right and left ends of thefirst cover plate 31 in such a manner that the side cover plate 33 canbend backwards due to guide means 34 provided between the first saddle 4and the side cover plate 33. More specifically, as shown in FIG. 7 andFIG. 8, the side cover plate 33 is bendable in longitudinal direction byhinged joints 35 provided to each of the right and left ends of thefirst cover plate 31. The guide means 34 provided to each side coverplate 33 have guiding structures provided above and below the side coverplates 33. One of the structures is now described. A guide plate 36 inhooked from plane view is fixed to each end of the first saddle 4. Aquartered circular guide passage 36 a is provided to each guide plate36. Roller 37 are protrudently provided to upper and lower ends of theside cover plate 33, and inserted into the guide passages 36 a. Besides,springs 38 are provided as force means between points around the centerof curvature of the guide passages 36 a and around the pin bodies 37.The side cover plate 33 is pulled to the side that the springs 38 rockrearward by the force means.

As shown in FIG. 9, the second cover plate 39 for covering the front,upper and lower sides of the first cover plate 31 is fixed integrallywith the first saddle 4 through connecting members 40. The second coverplate 39 has a square through hole 39 a through which the spindle head 8can move in lateral direction.

As shown in FIG. 10 and FIG. 11, the third cover plate 41 in U-shapedfrom plane view is fixed integrally with the column 2 on the front sideof the second cover plate 39. end of the first saddle 4. A quarteredcircular guide passage 36 a is provided to each guide plate 36. Roller37 are protrudently provided to upper and lower ends of the side coverplate 33, and inserted into the guide passages 36 a. Besides, springs 38are provided as force means between points around the center ofcurvature of the guide passages 36 a and around the pin bodies 37. Theside cover plate 33 is pulled to the side that the springs 38 rockrearward by the force means.

As shown in FIG. 9, the second cover plate 39 for covering the front,upper and lower sides of the first cover plate 31 is fixed integrallywith the first saddle 4 through connecting members 40. The second coverplate 39 has a square through hole 39 a through which the spindle head 8can move in lateral direction.

As shown in FIG. 10 and FIG. 11, the third cover plate 41 in U-shapedfrom plane view is fixed integrally with the column 2 on the front sideof the second cover plate 39. In this case, the third cover plate 41 hasa roughly square through hole 41 a for allowing the spindle head 8 tomove in vertical or lateral direction.

To form a machining center due to the basic structures of thus machinetool, the following not-illustrated structures are added. Those are, forexample, a tool magazine for putting many tools therein, and anautomatic tool exchange machine for tightly inserting a tool into thetip of the spindle 28 after receiving it from the tool magazine, orconversely returning the tool to the tool magazine after removing itfrom the tip end of the spindle 28, and a fence covering the wholestructures above the bed 1 at need.

Next, an explanation follows about how to operate thus structuredmachine tool.

The first saddle 4 and the spindle head 8 move in vertical direction f1by rotations of the servomotor 11. In this case, the first cover plate31, the side cover plate 33 and the second cover plate 39 move invertical direction integrally with the first saddle 4. The third coverplate 41 does not move in vertical direction because it is fixed on thecolumn 2. However, a through hole 41 provided to the third cover plate41 allows the spindle head 8 to move in vertical direction. During thisvertical movement, the first cover plate 31 and the side cover plates 33intercept a longitudinal space formed by a through hole 39 a of thesecond cover plate 39. Besides, the second cover plate 39, the firstcover plate 31 and the side cover plates 33 intercept a longitudinalspace formed by the through hole 41 a of the third cover plate 41.

The second saddle 6 and the spindle head 8 move in lateral direction f2through rotations of the servomotor 16. In this case, the first coverplate 31 moves in lateral direction integrally with the second saddle 6.According to this lateral movement, the side cover plate 33 moves inlateral direction. Though the second cover plate 39 and the third coverplate 41 do not laterally move, the through holes 39 a of the coverplate 39 and the through hole 41 a of the cover plate 41 allow thespindle head 8 to move in lateral direction.

When each side cover plate 33 moves in lateral direction, the pin bodies37 move, guided by the guide passages 36 a of the guide plates 36.According to this movement, the side cover plate 33 moves inlongitudinal direction around the hinged joints 35 due to force workedon the rollers 37.

For example, when the second saddle 6 moves to the most right side, theside cover plate 33 on the right side moves backward at an almost rightangle around the hinged joint 35 by an interaction between the guidepassage 36 a and the pin body 37 as shown in FIG. 12A. Conversely, whenthe second saddle 6 moves to the most left side, the side cover plate 33on the left side is situated in the same lateral direction as the firstcover plate 31 by an interaction between the guide passage 36 a and thepin body 37 as shown in FIG. 12B. Then, the side cover plates 33intercept a longitudinal space formed by the through hole 39 a of thesecond cover plate 39. The side cover plate 33 on the left side workssymmetrically to the side cover plate 33 on the right side. Hence, thelongitudinal space formed by the through hole 39 a of the second coverplate 39 is closed by the first cover plate 31 and the side cover plates33, 33 regardless of locations of the second saddle 6 in lateraldirection f2. Besides, a longitudinal space formed by the through hole41 a of the third cover plate 41 is closed by the second cover plate 39,the first cover plate 31 and the side cover plates 33, 33.

By rotations of the servomotor 27, the spindle head 8 moves inlongitudinal direction f3. Accordingly, the spindle 28 moves to anoptional position of the triaxial direction. In this case, while thespindle head 8 moves backward, the sealing means 32 prevents cuttingchips and coolant adhered to the circumference of the spindle head 8from intruding behind the first cover plate 31 by removing and droppingthem.

According to the triaxial movements of the spindle 28 and rotations ofthe tool fitted on the tip of the spindle 28 by the drive motor, theworkpiece fixed on the not-illustrated work table can be processed.

During processing of the workpiece, cutting chips and coolant generatedby the tool splash backward due to rotations of the tool. Cutting chipshaving passed through the through hole 41 a of the third cover plate 41collide to the second cover plate 39 and fall. Cutting chips havingpassed through the through hole 39 a of the second cover plate 39collide to the first cover plate 31 and the side cover plates 33 andfall. Therefore, the cutting chips and the coolant do not directly fallon the first saddle 4 and the second saddle 6 regardless of the optionalposition of the spindle head 8 within its moving range. Besides, thecutting chips are certainly shut off by plate members of great rigidity.

While the second saddle 6 moves in lateral direction, each spring 38pulls each pin body 37 of the side cover plates 33 toward the vicinityof the center of curvature on each guide passage 36 a to press the sidecover plates 33 on the circumference of the guide passage 36, therebypreventing backlash of the side cover plates 33 due to free space.

What is claimed is:
 1. A machine tool, comprising a bed (1), a column(2) installed fixedly on the bed (1), a first saddle (4) guided on afront surface of the column (2) movably in a vertical direction, asecond saddle (6) guided on a front surface of the first saddle (4)movably in a lateral direction with respect to the vertical direction, aspindle head (8) guided on the second saddle (6) movably in alongitudinal direction of the spindle head, wherein a first cover plate(31) is fixed to a front surface of the second saddle (6) in a manner soas to allow the longitudinal movement of the spindle head (8)therethrough, a side cover plate (33) is installed continuouslyconnected with each of right and left side ends of the first cover plate(31) so as to turn backward in a guided manner during the lateralmovement by a guiding effect of guiding means (34) for guiding providedbetween the side cover plates (33) and the first saddle (4), a secondcover plate (39) is fixed integrally with the first saddle (4) to covera front side of the first cover plate (31) and an upper side and a lowerside of the first cover plate (31) in such a manner that the spindlehead (8) can move in the lateral direction, and a third cover plate (41)is installed fixedly to a front side of the second cover plate (39) tocover the front surface of the column (2) in such a manner that thespindle head (8) can move in the vertical and lateral directions.
 2. Amachine tool as claimed in claim 1, wherein the first cover plate (31)has a through hole (8 a) into which the spindle head (8) is insertedmovably in the longitudinal direction, and a sealing means (32) isprovided between the through-hole (8 a) and the spindle head (8) to holdtheir interval substantially liquid-tightly.
 3. A machine tool asclaimed in claim 1, wherein arcuate guide passages (36 a) are providedto the guiding means (34).
 4. A machine tool as claimed in claim 3,wherein the second saddle (6) moves toward either one of right and leftsides of the first saddle, and the side cover plate (33) on the side ofthe second saddle (6) toward which the second saddle moves turnsbackward around a part connected with the first cover plate (31) by aguiding effect of the arcuate guide passages (36 a) on the guiding means(34).
 5. A machine tool as claimed in claim 3, wherein each side coverplate (33) is pulled in a direction perpendicular to the arcuate guidepassages (36 a) on the guiding means (34) by forcing means (38).